In general, high power applications such as motor controllers, inverters, converters, power supplies, or other control devices often utilize a number of circuit boards. Typically, these boards include power modules which house high-power electrical devices such as resistors and semiconductors, logic or customer interface circuit boards (e.g., motherboard) which house microprocessors or other logic devices for performing control functions, and storage or capacitor circuit boards which house charge storage devices and direct current (DC) power busses. For example, in the field of electronic motor controllers, it is commonplace to build a controller package as an assemblage of circuit boards including a power substrate module or other heat dissipating medium. Each of the circuit boards supports components and conducting paths for accomplishing various functions in the completed device.
Such motor controllers generally include control logic circuitry, charge storage circuitry and power components. The control logic circuitry, typically including programmable solid state circuits such as a programmable logic controller mounted on a motherboard or a separate logic circuit module, monitors operating parameters of the motor and generates control signals for driving the motor in accordance with a preset control routine and various operator inputs. The power components typically include diode rectifying circuits for receiving AC power from a source and converting it to DC power, and power transistors or similar solid state switching devices, such as insulated gate bi-polar transistors (IGBTs), for converting the DC power stored in the charge storage circuitry to controlled AC signals for driving the motor based upon the control signals produced by the control circuitry.
The power components are mounted on a power substrate module circuit board. The logic circuitry is typically mounted on a customer interface or mother circuit board, and the charge storage circuitry is mounted on a capacitor board.
These circuit board systems typically require module or circuit board interconnection systems (e.g., connectors, header assemblies, or other hardware) to interface each circuit board (e.g., the power substrate module, the customer interface board, the motherboard and capacitor board). Module interconnection systems often include pins bent at a 90.degree. angle. First ends of the pins insert into holes in the circuit boards or modules, and the second ends of the pins are inserted into holes in the motherboard. An insulating frame is provided between the first and second ends. The frame which is located proximate the 90.degree. bend in the pins is usually rectangularly shaped and provides a stable seat or structure between the motherboard and the module. The first and second ends of the pins are soldered to contact areas proximate the holes on the modules and the motherboard, respectively. Alternatively, module interconnection systems may include slot edge connectors, card connectors, or other printed circuit board (PCB) connectors, or the circuit boards may be interconnected with external wires, cables or connectors.
Such interconnection systems are not only expensive, bulky, and add to the cost of assembling the circuit board system, but create significant impedance matching problems in high power applications such as in motor controller applications. For example, motor controllers and high power circuits such as inverters, converters, and power supplies often must include snubbing circuits, or other resistive (R), capacitive (C), or inductive (L) networks to tune the circuit boards and reduce the parasitic inductive effects and capacitive effects associated with the circuit board interconnection systems. These parasitic inductance problems between circuit boards are amplified by the very high switching frequency and the power associated with power modules, particularly in the turnoff phase of inverter operation.
Additionally, circuit board systems utilized in power applications often generate a significant amount of heat, and require heat sinks or other thermal management systems to prevent the circuit boards and electrical devices from overheating. Heat sinks are typically metal components relatively large in size and can be secured to circuit boards or associated electrical devices to enhance heat dissipation therefrom. Conventional heat sinks typically add to the cost of assembly of the circuit board system. Therefore, applications such as motor control applications require circuit board systems which are optimized for superior heat dissipation.
Thus, there is a need for a circuit board system for a motor controller optimized to reduce parasitic inductance. There is also a need for a low cost motor controller circuit board system optimized for heat dissipation and ease of assembly.